1. Field of the Invention
The present disclosure relates to a head part of an annular combustion chamber and particularly but not exclusively relates to a head part of an annular gas turbine combustion chamber for a gas turbine.
2. Description of the Related Art
The operation of gas turbine engines is relatively well known and, as will be appreciated, requires presentation of fuel for combustion in order to generate thrust. In order to present that fuel, a fuel spray nozzle or burner is required. Referring to FIG. 1(a), which shows a first previously-proposed arrangement, the fuel burner (not shown) is typically located within an end wall or meter panel 10 such that the fuel spray is appropriately presented within the combustor parts of the gas turbine engine. It will be understood that the combustor parts of a gas turbine engine will generate significant heat and therefore thermal stressing as well as vibration and other factors may create significant wear upon the mountings for the spray nozzle. In such circumstances a burner collar 30 is generally provided within the end wall 10 which ensures that the fuel spray nozzle is appropriately presented. A heat shield 20 is also provided to protect the end wall 10 from the hot burner gases and from an unacceptably high radiation effect. Furthermore, upon repair and overhaul it is generally easier to replace the heat shield 20 rather than the end wall 10 within the gas turbine engine.
FIGS. 1(b) and 1(c) show similar head parts of an annular combustion chamber for second and third previously-proposed arrangements. Further examples are shown in U.S. Pat. No. 5,996,335, EP1975514, U.S. Pat. No. 5,956,955 and U.S. Pat. No. 5,894,732.
In each example, the burner collars 30 and hence burners are held in place by virtue of a holding part 22, which is fastened to the end wall 10 together with the heat shield 20.
In the case of the first previously-proposed arrangement shown in FIG. 1(a), the holding part 22 secures the burner collar 30 to the end wall 10 by virtue of a bolt tack welded to a washer 23. A location ring 12 is provided between the collar 30 and end wall 10. In the second previously-proposed arrangement, the burner collar 30 is held between two retaining washers 34, 36, which are in turn held in place by the heat shield 20 and holding part 22. The burner collar 30 of the third previously-proposed arrangement is held in place by a common holding part 22 shared between adjacent burner collars 30.
However, the previously-proposed arrangements require an excessive number of components, which add to the cost and weight of the combustor. Furthermore, additional time is required to assemble and dissemble the components, e.g. on first build or during an overhaul, and this further adds to the costs. On the first and third previously-proposed arrangements the head components can only be assembled from the cold side of the end wall, i.e. the side not facing the combustion chamber, which is less convenient to access. With the first and third previously-proposed arrangements the location ring 12 and burner collar 30 have to be “posted” through a slot (not shown) in the cowl and passed around the space between the cowl and the meter panel to the required burner position. This further complicates the installation process and adds weight to the cowl since the slot requires a cover plate and rivets.
Furthermore, in the case of the first and third previously-proposed arrangement, the components for each burner position have to be assembled or disassembled in sequence. For example, to remove the tenth burner seal/location ring, then the first to ninth burner seals have to be removed first.
The present disclosure therefore seeks to address these issues.